1. Field of the Invention
The present invention relates to a rotary head type magnetic recording/reproducing apparatus having a playback head for verifying a recorded state after recording to a magnetic tape (hereinafter described as "read-after-write"), and more particularly, to a rotary head type magnetic recording/reproducing apparatus capable of finding a recording error simultaneously with recording.
2. Description of the Prior Art
FIG. 5 is a plane view showing a rotary drum and the magnetic heads of a rotary head type magnetic recording/reproducing apparatus having conventional magnetic heads for read-after-write use, and FIG. 6 shows read-after-write according to this apparatus. The apparatus in FIGS. 5 and 6 is disclosed in the publication of Japanese laid-open patent Sho-63-171404.
In this apparatus, recording/reproducing heads A and B, and playback heads A' and B' are mounted on rotary drum 1. These magnetic heads A, B, A', B' are mounted spaced apart 90.degree. from each other on rotary drum 1. Playback head A' is for verifying the recorded state on a magnetic tape T for recording/reproducing head A, and the playback head B' is for verifying the recorded state for recording/reproducing head B.
In a recording mode, the magnetic tape T travels along the rotary drum 1 at a predetermined speed in the direction of arrow .alpha. in FIG. 6. In this state, when the rotary drum 1 is rotated in the direction of arrow .beta. in FIG. 5, the recording/reproducing heads A and B (having azimuth angles differing from each other) scan the magnetic tape T in a direction of arrow .gamma. of FIG. 6.
Accordingly, the recording/reproducing heads A and B perform, alternatively, recording at an azimuth angle differing from each other on the magnetic tape T to thereby form the recording tracks t1-t10. Further, scanning of each track is within the period that the rotary drum 1 rotates by 90.degree.. When the rotary drum 1 is further rotated by 90.degree. from the time when the scanning of recording track t1 by the recording/reproducing head A is terminated (delayed 180.degree. from the start of scanning by the same head A), recording/reproducing head B reaches the scanning starting point of the recording track t2 neighboring to the recording track t1, and scanning by head B is performed within the period when the rotary drum 1 is rotated by 90.degree.. That is to say, recording of 2 tracks (one frame) of the recording track t1 and t2 is performed in one rotation of the rotary drum 1.
Thus, the read-after-write of data recorded on the magnetic tape T is performed by the playback heads A' and B' as aforementioned, however, it is delayed one frame after recording. That is to say, as shown in FIG. 6, the playback head A' reaches the scanning starting point of the recording track t9 at a time when the recording/reproducing head A has completed recording of the recording track t9 and the recording/reproducing head B has completed the scanning of the recording track t10. Therefore, read-after-write is performed by delaying one frame. The read-after-write by the playback head B, is performed similarly by delaying one frame. Therefore, the positions (height in the axial direction of the rotary drum) of the playback heads A' and B' are such that read-after-write is performed by delaying one frame as aforementioned.
Further, the recording track t11 shown by the broken line in FIG. 6 shows that scanning is started by the recording/reproducing head A after the rotary drum 1 is turned by 90.degree. from the state shown in FIG. 6, and the read-after-write of the recording track t9 by the playback head A' is completed. The width of this track t11 is equal to the head width a of the recording/reproducing head A and it is a larger dimension by as much as the overwriting width (overlapped writing) c from the recording track width b after overwriting.
However, in this conventional rotary head type magnetic recording/reproducing apparatus, since the read-after-write is performed by delaying one frame (2 tracks) after recording, a time period of scanning time of over one frame elapses before any recording error is detected after recording, therefore, there is the problem that rapid finding of the recording error is not possible.